See Exclusive Photos from National Geographic’s Military Series ‘Chain of Command’

Afghanistan -- U.S. Marines aboard a transport aircraft seen in a production photo from National Geographic’s “Chain of Command.” The eight-part documentary series follows U.S. units around the world as they fight extremists from Africa to Afghanistan. Narrated by Chris Evans (“Captain America,” “The Avengers”), the series runs on Mondays at 9/8 central. (Cam Glendenning, special to Military Times/National Geographic)

An Iraqi Army soldier, seen in a production photo from National Geographic’s “Chain of Command.” The eight-part documentary series follows U.S. units around the world as they fight extremists from Africa to Afghanistan. Narrated by Chris Evans (“Captain America,” “The Avengers”), the series runs on Mondays at 9/8 central. (James Butler/National Geographic)

Afghanistan - A U.S. Navy lieutenant, seen in a production photo from National Geographic’s “Chain of Command.” The eight-part documentary series follows U.S. units around the world as they fight extremists from Africa to Afghanistan. Narrated by Chris Evans (“Captain America,” “The Avengers”), the series runs on Mondays at 9/8 central. (Cam Glendenning, special to Military Times/National Geographic)

Afghanistan -- U.S. and Afghan military members hold a meeting as seen in a production photo from National Geographic’s “Chain of Command.” The eight-part documentary series follows U.S. units around the world as they fight extremists from Africa to Afghanistan. Narrated by Chris Evans (“Captain America,” “The Avengers”), the series runs on Mondays at 9/8 central. (Cam Glendenning, special to Military Times/National Geographic)

Afghanistan -- U.S. Marines aboard a transport aircraft seen in a production photo from National Geographic’s “Chain of Command.” The eight-part documentary series follows U.S. units around the world as they fight extremists from Africa to Afghanistan. Narrated by Chris Evans (“Captain America,” “The Avengers”), the series runs on Mondays at 9/8 central. (Cam Glendenning, special to Military Times/National Geographic)

Afghanistan -- U.S. Marine reads a book on back of aircraft, seen in a production photo from National Geographic’s “Chain of Command.” The eight-part documentary series follows U.S. units around the world as they fight extremists from Africa to Afghanistan. Narrated by Chris Evans (“Captain America,” “The Avengers”), the series runs on Mondays at 9/8 central. (Cam Glendenning, special to Military Times/National Geographic)

Chad -- Chadian soldiers, seen in a production photo from National Geographic’s “Chain of Command.” The eight-part documentary series follows U.S. units around the world as they fight extremists from Africa to Afghanistan. Narrated by Chris Evans (“Captain America,” “The Avengers”), the series runs on Mondays at 9/8 central. (Cam Glendenning, special to Military Times/National Geographic)

Afghanistan - US Marines aboard a transport aircraft seen in a production photo from National Geographic’s “Chain of Command.” The eight-part documentary series follows U.S. units around the world as they fight extremists from Africa to Afghanistan. Narrated by Chris Evans (“Captain America,” “The Avengers”), the series runs on Mondays at 9/8 central. (National Geographic/Cam Glendenning, special to the Military Times)

Afghanistan -- An Afghan soldier is seen in a production photo from National Geographic’s “Chain of Command.” The eight-part documentary series follows U.S. units around the world as they fight extremists from Africa to Afghanistan. Narrated by Chris Evans (“Captain America,” “The Avengers”), the series runs on Mondays at 9/8 central. (Cam Glendenning, special to Military Times/National Geographic)